Electromagnetic sound reproducer



Oct. -28, 1930. R. 1.. BROWN -1,779,728

ELECTROMAGNETIC SOUND REPRODUCER Filed Jan. 29, 1927 2 Sheets-Sheet l INVENTOR.

ATTORNEY R. L. BROWN ELECTROMAGNETIC SOUND REPRODUCER Filed Jan. 29, 1927 2 Sheets-Sheet 2 INVENTOR. favfl 1.,5204022 TTORNEY Patented Oct. 28, 1930 UNITED STATES PATENT OFFICE RALPH L. BROWN, NEVTARK, NEW JERSEY, ASSIGNOR- TO BRANDES LABORATORIES, INC., OF NEWARK, NEW JERSEY, A CORPORATION OF NEW JERSEY ELECTROMAGNETIC SOUND REPRODUCER Application filed January 29, 1927. Serial No. 164,571.

liily invention relates broadly to electromagnetic sound reproducers and more particularly to loud speakers of the conical diaphragm type.

One of the objects of my invention is to provide a loud speaker having a conical shaped sound reproducing diaphragm where the diaphragm is arranged within a sound reflecting frame the peripheral edge of the sound reproducing diaphragm being substantially free, the diaphragm being supported from the apex by a driving member which connects with the driving armature.

Another object of my invention is to provide a construction of electromagnetic sound reproducer in which a frame structure provides a housing for a conical shaped sound reproducing diaphragm, the diaphragm being supported at its apex from an electromagnetic: driving mechanism and the free peripheral edge of the diaphragm being spaced from the frame structure to allow free vibration of the diaphragm.

Another object of my invention is to provide a construction of electromagnetic sound reproducer having a conical shaped sound reproducing diaphragm supported at its periphery and having its free peripheral edge spaced from a surrounding frame structure which conforms with the shape of the base of the diaphragm, the free edge of the diaphragm being reenforced to prevent undesirable blasting at large amplitudes.

My invention will be more clearly understood from the specification hereinafter following by reference to the accompanying drawings in which:

Figure 1 is a cross-sectional view taken through the electromagnetic sound reproducer and showing the arrangement of parts thereof; and Fig. 2 is a cross-sectional view taken on line 22 of Fig. 1 showing the method of positively spacing the conical shaped diaphragm from the frame which surrounds the base portion of the diaphragm.

Referring to the drawings in more detail reference character 1 designates a base structure for the electromagnetic sound reproducer having a vertically extending member 2 thereon supporting a housing 3 at the top thereof which forms an enclosure for elce tromagnctic operating mechanism constituting the driver. The electromagnetic operating mechanism includes an electromagnetic system which is carried by a rotatable plate member 4 provided with gear teeth 5 cut in the rear plate portion thereof which mesh with the teeth of pinion 6 by which adjustment ofthe electromagnetic driving mechanism may be effected. The pinion 6 is carried by a rotatable shaft member 7 which is journaled in the upstanding lug 8. A frame structure is supported from the base 1 and consists of an annular plate member 9 and a parabolic reflector 10 secured together by means of bolt members 11 at points spaced about the peripheral edges of the plate member 9 and parabolic reflector 10. The parabolic reflector 10 is provided with an aperture 12 adjacent the rear thereof, the aperture being closed by an ornamental grille 14 secured in position by bolt 1 iembers 15 passing through gasket 16 and ring member 17. A knob 18 is provided on shaft 7 for permitting adjustment of the electromagnetic driving mechanism from the outside of the electromagnetic sound reproducer. A bearing 19 is provided for steadying the shaft 7, the bearing being supported from strip 20 carried by one of the bolt members 15. The refleeting surface 10 is rigidly connected with the upstanding lug member 8 on the electromagnetic driver 3 by means of a brace 19 connected by bolt member 21 passing through the reflecting wall 10 and by the bolt member 22 passing through the lug 8. The frame structure constituted in part by the plate member 9 is apertured at 23 and through this aperture the conical shaped sound reproduc ing, diaphragm 2% projects. The conical shaped sound reproducing diaphragm 2-l is supported at its apex by means of telescopically arranged apex pieces 25 and which fit on opposite sides of the diaphragm and are provided with a screw chuck member 27 passing through the apex of the conical shaped sound reproducing diaphragm and clamped upon the link member 28. The edge of the sound reproducing diaphragm is free as represented at 29, and in order to locate the base of the conical shaped sound reproducing diaphragm within the frame structure, I provide flexible strip members 30 which extend from the bolt members 11 to the peripheral edge of the conical shaped sound reproducing diaphragm. The sound reproducing diaphragm in this manner floats freely. within the frame structure which surrounds the base 1 vention of paper noises normally present in a free edge cone under conditions of vibration at excessive amplitudes. Connection 1s establlshed with the electromagnetic driver within the loud speaker through a flexible lead 32 which passes through an aperture 33 in the wall of the sound reflecting surface 10 for providing a connection with the loud speaker. I I

The structure of the electromagnetic sound reproducer of my invention has proven highly practical for processes of manufacture and successful and efficient in its operation.

Sound emanates from both sides of the conical shaped sound reproducing diaphragm and is subjected to reflection by the walls of the. frame structure, permitting the sound to be directed over a large area.

While I have described my invention in one of its preferred embodiments, I desire that it be understood that modifications may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

lVhat I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. A sound reproducer comprising a frame structure, a pair of plate members secured on opposite sides of said frame structure, an actuating driver carried by said frame structure, a conical shaped sound reproducing diaphragm supported by said driver, said sound reproducing diaphragm having a substantially free edge and a mulitiplicity of flexible strip members extending radially from the peripheral edge of said conical shaped sound reproducing diaphragm and connected to the outer limits of said plate members for centrally locating said conical shaped sound reproducing diaphragm with respect to said plate members.

. 2. A sound reproducer comprising a supporting member, an actuating driver carried by said supporting member, a conical shaped sound reproducing diaphragm actuated by. said actuating driver, said diaphragm having a substantially free peripheral edge, a

In order to prevent blasting sound reflectin surface carried by said supporting member, and a plurality of strip members extending from positions around said sound reflecting surface for centrally locating the free peripheral edge of said conical shaped sound reproducing diaphragm with ing a substantially free peripheral edge, a

soundreflecting surface carried by said supporting member, and independent means ex tending from separated points around said sound reflecting surface and connected with the free peripheral edge of said sound reproducing diaphragm for centrally locating said diaphragm with respect to said sound reflecting surface.

4.. A sound reproducer comprising a supporting member, an actuating driver carried by said supporting member, a conical shaped sound reproducing diaphragm operated by said actuating driver, said diaphragm having a substantially free peripheral edge, a V

' sound, reflecting surface carried by said supporting member and a plurality 'of independent means extending from different points around said sound reflecting surface and connected at spaced intervals with the free peripheral edge of said conical shaped sound reproducing diaphragm for centrally locating said sound re] )roducing diaphragm with respect to said sound reflecting surface. 5. In a loud speaker reproducer a support ing member, an actuating driver carried by said supporting member, a pair of sound reflecting surfaces secured on opposite of said supporting member, each of said surfaces being apertured for the free passage of sound waves therethrough, a conical shaped sound reproducing diaphragm supported by said actuating driver and having its free peripheral edge centrally located with respect to said sound reflecting surfaces, means for positively'spacing .thefree peripheral edge of said sound reproducing diaphragm from said sound reflecting surfaces and separate means secured to the free peripheral edge of said sound reproducing diaphragm for preventing blasting of the edge of said diaphragm at large amplitudes.

V In testimony whereof I afliX my signature. 

